U.S. patent number 9,524,173 [Application Number 14/511,026] was granted by the patent office on 2016-12-20 for fast reboot for a switch.
This patent grant is currently assigned to BROCADE COMMUNICATIONS SYSTEMS, INC.. The grantee listed for this patent is BROCADE COMMUNICATIONS SYSTEMS, INC.. Invention is credited to Pasupathi Duraiswamy, Manjunath A. G. Gowda, Vidyasagara R. Guntaka, Suresh Vobbilisetty.
United States Patent |
9,524,173 |
Guntaka , et al. |
December 20, 2016 |
Fast reboot for a switch
Abstract
One embodiment of the present invention provides a switch. The
switch includes a packet processor, a persistent storage module,
and a boot-up management module. The packet processor identifies a
switch identifier associated with the switch in the header of a
packet. The persistent storage module stores configuration
information of the switch in a first table in a local persistent
storage. This configuration information is included in a
configuration file, and the first table includes one or more
columns for the attribute values of the configuration information.
The boot-up management module loads the attribute values to
corresponding switch modules from the first table without
processing the configuration file.
Inventors: |
Guntaka; Vidyasagara R. (San
Jose, CA), Vobbilisetty; Suresh (San Jose, CA), Gowda;
Manjunath A. G. (San Jose, CA), Duraiswamy; Pasupathi
(Milpitas, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
BROCADE COMMUNICATIONS SYSTEMS, INC. |
San Jose |
CA |
US |
|
|
Assignee: |
BROCADE COMMUNICATIONS SYSTEMS,
INC. (San Jose, CA)
|
Family
ID: |
55655500 |
Appl.
No.: |
14/511,026 |
Filed: |
October 9, 2014 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20160103692 A1 |
Apr 14, 2016 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F
8/35 (20130101); H04L 45/74 (20130101); H04L
41/046 (20130101); H04L 41/0853 (20130101); G06F
9/4401 (20130101); H04L 41/0806 (20130101); H04L
41/0856 (20130101); H04L 41/0233 (20130101); H04L
41/0869 (20130101) |
Current International
Class: |
G06F
9/00 (20060101); G06F 9/44 (20060101); H04L
12/24 (20060101); H04L 12/741 (20130101) |
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Feb 2014 |
|
WO |
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|
Primary Examiner: Choudhury; Zahid
Attorney, Agent or Firm: Yao; Shun Park, Vaughan, Fleming
& Dowler LLP
Claims
What is claimed is:
1. A switch, comprising: a packet processor configured to identify
a switch identifier associated with the switch in a header of a
packet; a persistent storage module configured to store
configuration information of the switch in a first table in an
object relational database in a local persistent storage, wherein
the configuration information is included in a configuration file,
and wherein the first table includes one or more columns for
attribute values of the configuration information; and a boot-up
management module configured to load the attribute values to
corresponding switch hardware modules from the first table the
object relational database without processing the configuration
file.
2. The switch of claim 1, wherein the boot-up management module is
further configured to determine whether the configuration file has
been changed during a reboot of the switch.
3. The switch of claim 2, wherein, in response to determining that
the configuration file has been changed, the boot-up management
module is further configured to: determine a changed portion of the
configuration file; and update the first table based on the changed
portion.
4. The switch of claim 1, wherein the boot-up management module is
further configured to maintain an order in which the attribute
values are loaded to the switch hardware modules.
5. The switch of claim 4, wherein the boot-up management module
maintains the order based on a sequence table, wherein the sequence
table includes one or more execution passes, and wherein the
boot-up management module sequentially loads attribute values of
one pass at time to the switch hardware modules.
6. The switch of claim 5, wherein a pass includes one or more
features which are loaded to the switch hardware modules during the
pass, and wherein a feature corresponds to a collection of
attribute values.
7. The switch of claim 6, wherein the boot-up management module
maintains an order of attribute values of a feature based on a
dependency map, wherein the dependency map indicates a dependency
based on a Unified Modeling Language (UML) model.
8. The switch of claim 6, wherein a pass is associated with a
processing indicator which indicates whether the features of a pass
are loaded to the switch hardware modules serially or in
parallel.
9. The switch of claim 4, wherein the sequence table is associated
with a scope, wherein the scope indicates a subset of attribute
values of a feature to be loaded to the switch hardware
modules.
10. The switch of claim 4, wherein the sequence table is expressed
based on Extensible Markup Language (XML).
11. The switch of claim 1, further comprising a fabric switch
module configured to maintain a membership in a network of
interconnected switches, wherein the network of interconnected
switches is identified by a fabric identifier.
12. A method, comprising: identifying a switch identifier
associated with a switch in a header of a packet; storing
configuration information of the switch in a first table in an
object relational database in a local persistent storage, wherein
the configuration information is included in a configuration file,
and wherein the first table includes one or more columns for
attribute values of the configuration information; and loading the
attribute values to corresponding switch hardware modules from the
first table in the object relational database without processing
the configuration file.
13. The method of claim 12, further comprising determining whether
the configuration file has been changed during a reboot of the
switch.
14. The method of claim 13, wherein, in response to determining
that the configuration file has been changed, the method further
comprises: determining a changed portion of the configuration file;
and updating the first table based on the changed portion.
15. The method of claim 12, further comprising maintaining an order
in which the attribute values are loaded to the switch hardware
modules.
16. The method of claim 15, wherein the order is maintained based
on a sequence table, wherein the sequence table includes one or
more execution passes, and wherein the boot-up management module
sequentially loads attribute values of one pass at time to the
switch hardware modules.
17. The method of claim 16, wherein a pass includes one or more
features which are loaded to the switch hardware modules during the
pass, and wherein a feature corresponds to a collection of
attribute values.
18. The method of claim 17, wherein an order of attribute values of
a feature is maintained based on a dependency map, wherein the
dependency map indicates a dependency based on a Unified Modeling
Language (UML) model.
19. The method of claim 17, wherein a pass is associated with a
processing indicator which indicates whether the features of a pass
are loaded to the switch hardware modules serially or in
parallel.
20. The method of claim 15, wherein the sequence table is
associated with a scope, wherein the scope indicates a subset of
attribute values of a feature to be loaded to the switch hardware
modules.
21. The method of claim 15, wherein the sequence table is expressed
based on Extensible Markup Language (XML).
22. The method of claim 12, further comprising maintaining a
membership in a network of interconnected switches, wherein the
network of interconnected switches is identified by a fabric
identifier.
23. A computer system; comprising: a processor; a storage device
coupled to the processor and storing instructions that when
executed by the processor cause the processor to perform a method,
the method comprising: identifying a switch identifier associated
with a switch in a header of a packet; storing configuration
information of the switch in a first table in an object relational
database in a local persistent storage, wherein the configuration
information is included in a configuration file, and wherein the
first table includes one or more columns for attribute values of
the configuration information; and loading the attribute values to
corresponding switch hardware modules from the first table in the
object relational database without processing the configuration
file.
24. The computer system of claim 23, wherein the method further
comprises maintaining an order in which the attribute values are
loaded to the switch hardware modules, wherein the order is
maintained based on a sequence table, wherein the sequence table
includes one or more execution passes, and wherein the boot-up
management module sequentially loads attribute values of one pass
at time to the switch hardware modules.
25. The computer system of claim 24, wherein a pass includes one or
more features which are loaded to the switch hardware modules
during the pass, and wherein a feature corresponds to a collection
of attribute values.
26. The computer system of claim 25, wherein a pass is associated
with a processing indicator which indicates whether the features of
a pass are loaded to the switch hardware modules serially or in
parallel.
Description
RELATED APPLICATION
The present disclosure is related to U.S. patent application Ser.
No. 13/087,239, titled "Virtual Cluster Switching," by inventors
Suresh Vobbilisetty and Dilip Chatwani, filed 14 Apr. 2011, the
disclosure of which is incorporated by reference herein.
BACKGROUND
Field
The present disclosure relates to communication networks. More
specifically, the present disclosure relates to a method for a
constructing a scalable system that facilitates persistent storage
in a switch.
Related Art
The exponential growth of the Internet has made it a popular
delivery medium for a variety of applications running on physical
and virtual devices. Such applications have brought with them an
increasing demand for bandwidth. As a result, equipment vendors
race to build larger and faster switches with versatile
capabilities. However, the size of a switch cannot grow infinitely.
It is limited by physical space, power consumption, and design
complexity, to name a few factors. Furthermore, switches with
higher capability are usually more complex and expensive. More
importantly, because an overly large and complex system often does
not provide economy of scale, simply increasing the size and
capability of a switch may prove economically unviable due to the
increased per-port cost.
A flexible way to improve the scalability of a switch system is to
build a fabric switch. A fabric switch is a collection of
individual member switches. These member switches form a single,
logical switch that can have an arbitrary number of ports and an
arbitrary topology. As demands grow, customers can adopt a "pay as
you grow" approach to scale up the capacity of the fabric
switch.
Meanwhile, a switch, an individual or a member switch of a fabric
switch, continues to store more configuration information as the
switch participates in network virtualizations, partitions, and
switch groups, and operates on a plurality of network protocols of
different network layers. This configuration needs to be applied to
the switch when the switch powers up, and thus, should be
persistent. A switch typically stores such configuration
information in a local storage in an unstructured format. The
switch reads the information during booting up (i.e., powering up),
and loads the information into memory. Managing persistent storage
in unstructured format is inefficient and requires runtime
structuring.
While persistent storage brings many desirable features to a
switch, some issues remain unsolved in efficiently facilitating
persistent storage in a structured way in a switch.
SUMMARY
One embodiment of the present invention provides a switch. The
switch includes a packet processor, a persistent storage module,
and a boot-up management module. The packet processor identifies a
switch identifier associated with the switch in the header of a
packet. The persistent storage module stores configuration
information of the switch in a first table in a local persistent
storage. This configuration information is included in a
configuration file, and the first table includes one or more
columns for the attribute values of the configuration information.
The boot-up management module loads the attribute values to
corresponding switch modules from the first table without
processing the configuration file.
In a variation on this embodiment, the boot-up management module
also determines whether the configuration file has been changed
during a reboot of the switch.
In a further variation, in response to determining that the
configuration file has been changed, boot-up management module
determines a changed portion of the configuration file and updates
the first table based on the changed portion.
In a variation on this embodiment, the boot-up management module
maintains the order in which the attribute values are loaded to the
switch modules.
In a further variation, the boot-up management module maintains the
order based on a sequence table. The sequence table includes one or
more execution passes. The boot-up management module sequentially
loads attribute values of one pass at time to the switch
modules.
In a further variation, a pass includes one or more features, which
are loaded to the processing hardware during the pass. A feature
corresponds to a collection of attribute values.
In a further variation, the boot-up management module maintains the
order of attribute values of a feature based on a dependency map.
The dependency map indicates a dependency based on a Unified
Modeling Language (UML) model.
In a further variation, a pass is associated with a processing
indicator which indicates whether the features of a pass are loaded
to the switch modules serially or in parallel.
In a further variation, the sequence table is associated with a
scope. This scope indicates a subset of attribute values of a
feature to be loaded to the switch modules.
In a further variation, the sequence table is expressed based on
Extensible Markup Language (XML).
In a variation on this embodiment, the switch also includes a
fabric switch module which maintains a membership in a fabric
switch. The fabric switch includes a plurality of switches and
operates as a single switch.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1A illustrates an exemplary network with persistent storage
framework support, in accordance with an embodiment of the present
invention.
FIG. 1B illustrates an exemplary persistent storage framework
support in a switch, in accordance with an embodiment of the
present invention.
FIG. 2 illustrates an exemplary object identifier generated by a
persistent storage framework in a switch, in accordance with an
embodiment of the present invention.
FIG. 3 illustrates exemplary base classes for supporting a
persistent storage framework in a switch, in accordance with an
embodiment of the present invention.
FIG. 4A illustrates an exemplary Unified Modeling Language (UML)
model of classes of a switch with a persistent storage framework,
in accordance with an embodiment of the present invention.
FIG. 4B illustrates an exemplary Extensible Markup Language (XML)
representation of a class corresponding to a switch with a
persistent storage framework, in accordance with an embodiment of
the present invention.
FIG. 4C illustrates exemplary tables generated by a persistent
storage framework in a switch, in accordance with an embodiment of
the present invention.
FIG. 4D illustrates an exemplary table representing a one-to-many
association, which is generated by in a persistent storage
framework in a switch, in accordance with an embodiment of the
present invention.
FIG. 5A presents a flowchart illustrating the process of a
persistent storage framework of a switch generating auxiliary
tables for an inheritance chain in a persistent storage, in
accordance with an embodiment of the present invention.
FIG. 5B presents a flowchart illustrating the process of a
persistent storage framework of a switch generating class tables in
a persistent storage, in accordance with an embodiment of the
present invention.
FIG. 5C presents a flowchart illustrating the process of a
persistent storage framework of a switch generating an auxiliary
table representing an one-to-many relationship in a persistent
storage, in accordance with an embodiment of the present
invention.
FIG. 5D presents a flowchart illustrating the process of a
persistent storage framework of a switch updating tables in a
persistent storage, in accordance with an embodiment of the present
invention.
FIG. 6 illustrates an exemplary fast reboot of a switch with
persistent storage framework, in accordance with an embodiment of
the present invention.
FIG. 7A illustrates an exemplary dependency map generated by a
persistent storage framework in a switch, in accordance with an
embodiment of the present invention.
FIG. 7B illustrates an exemplary sequence table which provides an
order during a fast reboot of a switch, in accordance with an
embodiment of the present invention.
FIG. 8A presents a flowchart illustrating the initial boot up
process of a switch with a persistent storage framework, in
accordance with an embodiment of the present invention.
FIG. 8B presents a flowchart illustrating the fast reboot process
of a switch with a persistent storage framework, in accordance with
an embodiment of the present invention.
FIG. 8C presents a flowchart illustrating the process of a switch
with a persistent storage framework using a sequence table for the
fast reboot process, in accordance with an embodiment of the
present invention.
FIG. 9 illustrates an exemplary switch with a persistent storage
framework and a fast reboot support, in accordance with an
embodiment of the present invention.
In the figures, like reference numerals refer to the same figure
elements.
DETAILED DESCRIPTION
The following description is presented to enable any person skilled
in the art to make and use the invention, and is provided in the
context of a particular application and its requirements. Various
modifications to the disclosed embodiments will be readily apparent
to those skilled in the art, and the general principles defined
herein may be applied to other embodiments and applications without
departing from the spirit and scope of the present invention. Thus,
the present invention is not limited to the embodiments shown, but
is to be accorded the widest scope consistent with the claims.
Overview
In embodiments of the present invention, the problem of efficiently
rebooting a switch is solved by storing configuration information
of the switch in a persistent storage, such as an object relational
database. During reboot, the configuration information is loaded
into the switch modules (e.g., processing hardware of the switch,
such as an application-specific integrated circuit (ASIC) chips)
from the persistent storage without applying the configuration
information to the switch.
A switch, individual or a member switch of a fabric switch, stores
configuration information (e.g., information associated with the
operations of the switch), often in a configuration file. Such
configuration information can be related to network
virtualizations, partitions, and switch groups, and a plurality of
network protocols of different network layers. The attribute values
(e.g., parameters) of the configuration are applied to the switch
(e.g., loaded to the switch modules) when the switch boots up
(i.e., when the switch powers up).
Furthermore, before applying the configuration, the switch
validates whether the configuration is correct and cross-checks
whether the configuration includes any conflict. Moreover, during
the boot up process, the switch reads and parses the attribute
values stored in an unstructured format. The switch structures the
attribute values during runtime, which is inefficient. As a result,
each time the switch reboots, even when the switch's configuration
information is not changed, the switch goes through this extensive
configuration process, which can be inefficient and cause delay to
network convergence.
To solve this problem, the switch is equipped with a persistent
storage framework which stores the configuration information in a
local persistent storage. This configuration information is loaded
from this persistent storage to the switch modules (e.g., ASIC
chips of the switch). The switch modules can include information
based on which the switch processes packets (e.g., determines
output ports for packets). During the initial boot up of the
switch, the switch validates, cross-checks, and executes the
configuration information from the configuration file and loads the
corresponding attribute values into the switch modules.
Furthermore, the framework stores these attribute values in the
persistent storage (e.g., an object relational database) of the
switch. When the switch reboots, the switch checks whether the
configuration information has been changed. Upon detecting one or
more changes, the framework locates where the changes are and
updates the corresponding persistent storage accordingly. If no
change is detected, or the changes have been incorporated, the
switch loads the attribute values from its persistent storage to
the switch modules. In this way, the switch provides a fast reboot
by bypassing the processing of the configuration file, and its
corresponding extensive execution, cross-checks, and validations of
the configuration information.
Segments of configuration information often depend on each other.
For example, a port should be configured before associating the
port with a port channel (e.g., for a trunked link). Typically, the
switch processes the configuration information sequentially from
the configuration file. A user (e.g., a network administrator) can
enforce the dependency in configuration by including configuration
information in the configuration file in a proper order. The proper
order refers to a sequence of execution for the configuration file
which allows the switch to be configured properly during the boot
up process. However, since embodiments of the present invention
bypass processing of the configuration file, dependency in the
configuration information may not be enforced by the configuration
file.
To solve this problem, the switch is equipped with a sequence
table, which includes one or more execution passes (e.g., steps),
and for each pass, includes one or more features that should be
loaded to the switch modules during that pass. The switch
sequentially loads configuration information of one pass at time,
and sequentially loads attribute values of a respective feature in
the order of the appearance of the feature in the pass to the
switch modules. In this way, the switch provides a loading order
for its fast reboot process. In this disclosure, the description in
conjunction with FIGS. 1-5 is associated with persistent storage in
the switch; and the description in conjunction with FIG. 6 and
onward provides more details on fast reboot process of the
switch.
In some embodiments, the framework supports Model Driven
Architecture (MDA), Object Oriented Programming (OOP), and/or
Model/View/Controller (MVC) design patterns to facilitate modular
development and operation of the units. The framework can also
support class frameworks based on Unified Modeling Language (UML).
Upon receiving class models (e.g., class name, attributes, and
methods) and their relations based on UML, the framework
automatically generates the corresponding code, thereby ensuring
structure in the operational units of a switch. In some
embodiments, the class models are expressed in YANG, which is a
data modeling language used to model configuration and state data
manipulated by the Network Configuration Protocol (NETCONF).
Since the units operate on the framework in a modular way, their
associated attribute values can be stored in a persistent storage
in a structured way. In some embodiments, the framework uses
Object-Relational Mapping to store the attribute values of the
units in a structured way in an object relational database. The
framework allows different classes to be defined for a unit based
on MDA, OOP, and/or MVC design patterns. The framework then
seamlessly maps a respective class to a database table and
vice-versa. Furthermore, the framework also seamlessly represents
the relationships among the classes (e.g., an association or a
composition) in the database. As a result, when a unit becomes
operational on the switch, attribute values associated with a
respective class in that unit is automatically loaded from the
database. Moreover, if a class changes (e.g., a new attribute or a
new relationship), the framework seamlessly incorporates that
change into the database.
In some embodiments, the switch can be a member switch of a fabric
switch. The switch can include one or more units which allow the
switch to join and operate as a member switch of the fabric switch.
These units can also run on the framework. In a fabric switch, any
number of switches coupled in an arbitrary topology may logically
operate as a single switch. The fabric switch can be an Ethernet
fabric switch or a virtual cluster switch (VCS), which can operate
as a single Ethernet switch. Any member switch may join or leave
the fabric switch in "plug-and-play" mode without any manual
configuration. In some embodiments, a respective switch in the
fabric switch is a Transparent Interconnection of Lots of Links
(TRILL) routing bridge (RBridge). In some further embodiments, a
respective switch in the fabric switch is an Internet Protocol (IP)
routing-capable switch (e.g., an IP router).
It should be noted that a fabric switch is not the same as
conventional switch stacking. In switch stacking, multiple switches
are interconnected at a common location (often within the same
rack), based on a particular topology, and manually configured in a
particular way. These stacked switches typically share a common
address, e.g., an IP address, so they can be addressed as a single
switch externally. Furthermore, switch stacking requires a
significant amount of manual configuration of the ports and
inter-switch links. The need for manual configuration prohibits
switch stacking from being a viable option in building a
large-scale switching system. The topology restriction imposed by
switch stacking also limits the number of switches that can be
stacked. This is because it is very difficult, if not impossible,
to design a stack topology that allows the overall switch bandwidth
to scale adequately with the number of switch units.
In contrast, a fabric switch can include an arbitrary number of
switches with individual addresses, can be based on an arbitrary
topology, and does not require extensive manual configuration. The
switches can reside in the same location, or be distributed over
different locations. These features overcome the inherent
limitations of switch stacking and make it possible to build a
large "switch farm," which can be treated as a single, logical
switch. Due to the automatic configuration capabilities of the
fabric switch, an individual physical switch can dynamically join
or leave the fabric switch without disrupting services to the rest
of the network.
Furthermore, the automatic and dynamic configurability of the
fabric switch allows a network operator to build its switching
system in a distributed and "pay-as-you-grow" fashion without
sacrificing scalability. The fabric switch's ability to respond to
changing network conditions makes it an ideal solution in a virtual
computing environment, where network loads often change with
time.
In this disclosure, the term "fabric switch" refers to a number of
interconnected physical switches which form a single, scalable
logical switch. These physical switches are referred to as member
switches of the fabric switch. In a fabric switch, any number of
switches can be connected in an arbitrary topology, and the entire
group of switches functions together as one single, logical switch.
This feature makes it possible to use many smaller, inexpensive
switches to construct a large fabric switch, which can be viewed as
a single logical switch externally. Although the present disclosure
is presented using examples based on a fabric switch, embodiments
of the present invention are not limited to a fabric switch.
Embodiments of the present invention are relevant to any computing
device that includes a plurality of devices operating as a single
device.
The term "end device" can refer to any device external to a fabric
switch. Examples of an end device include, but are not limited to,
a host machine, a conventional layer-2 switch, a layer-3 router, or
any other type of network device. Additionally, an end device can
be coupled to other switches or hosts further away from a layer-2
or layer-3 network. An end device can also be an aggregation point
for a number of network devices to enter the fabric switch. An end
device hosting one or more virtual machines can be referred to as a
host machine. In this disclosure, the terms "end device" and "host
machine" are used interchangeably.
The term "switch" is used in a generic sense, and it can refer to
any standalone or fabric switch operating in any network layer.
"Switch" should not be interpreted as limiting embodiments of the
present invention to layer-2 networks. Any device that can forward
traffic to an external device or another switch can be referred to
as a "switch." Any physical or virtual device (e.g., a virtual
machine/switch operating on a computing device) that can forward
traffic to an end device can be referred to as a "switch." Examples
of a "switch" include, but are not limited to, a layer-2 switch, a
layer-3 router, a TRILL RBridge, or a fabric switch comprising a
plurality of similar or heterogeneous smaller physical and/or
virtual switches.
The term "edge port" refers to a port on a fabric switch which
exchanges data frames with a network device outside of the fabric
switch (i.e., an edge port is not used for exchanging data frames
with another member switch of a fabric switch). The term
"inter-switch port" refers to a port which sends/receives data
frames among member switches of a fabric switch. The terms
"interface" and "port" are used interchangeably.
The term "switch identifier" refers to a group of bits that can be
used to identify a switch. Examples of a switch identifier include,
but are not limited to, a media access control (MAC) address, an
Internet Protocol (IP) address, and an RBridge identifier. Note
that the TRILL standard uses "RBridge ID" (RBridge identifier) to
denote a 48-bit intermediate-system-to-intermediate-system (IS-IS)
System ID assigned to an RBridge, and "RBridge nickname" to denote
a 16-bit value that serves as an abbreviation for the "RBridge ID."
In this disclosure, "switch identifier" is used as a generic term,
is not limited to any bit format, and can refer to any format that
can identify a switch. The term "RBridge identifier" is also used
in a generic sense, is not limited to any bit format, and can refer
to "RBridge ID," "RBridge nickname," or any other format that can
identify an RBridge.
The term "packet" refers to a group of bits that can be transported
together across a network. "Packet" should not be interpreted as
limiting embodiments of the present invention to layer-3 networks.
"Packet" can be replaced by other terminologies referring to a
group of bits, such as "message," "frame," "cell," or
"datagram."
Network Architecture
FIG. 1A illustrates an exemplary network with persistent storage
framework support, in accordance with an embodiment of the present
invention. As illustrated in FIG. 1A, a network 100 includes
switches 101, 102, 103, 104, and 105. An end device 112 is coupled
to switch 102. In some embodiments, end device 112 is a host
machine, hosting one or more virtual machines. End device 112 can
include a hypervisor, which runs one or more virtual machines. End
device 112 can be equipped with a Network Interface Card (NIC) with
one or more ports. End device 112 couples to switch 102 via the
ports of the NIC.
In some embodiments, network 100 is a TRILL network and a
respective switch of network 100, such as switch 102, is a TRILL
RBridge. Under such a scenario, communication among the switches in
network 100 is based on the TRILL protocol. For example, upon
receiving an Ethernet frame from end device 112, switch 102
encapsulates the received Ethernet frame in a TRILL header and
forwards the TRILL packet. In some further embodiments, network 100
is an IP network and a respective switch of network 100, such as
switch 102, is an IP-capable switch, which calculates and maintains
a local IP routing table (e.g., a routing information base or RIB),
and is capable of forwarding packets based on its IP addresses.
Under such a scenario, communication among the switches in network
100 is based on IP. For example, upon receiving an Ethernet frame
from end device 112, switch 102 encapsulates the received Ethernet
frame in an IP header and forwards the IP packet.
In some embodiments, network 100 is a fabric switch (under such a
scenario, network 100 can also be referred to as fabric switch
100). Fabric switch 100 is assigned with a fabric switch
identifier. A respective member switch of fabric switch 100 is
associated with that fabric switch identifier. This allows the
member switch to indicate that it is a member of fabric switch 100.
In some embodiments, whenever a new member switch joins fabric
switch 100, the fabric switch identifier is automatically
associated with that new member switch. Furthermore, a respective
member switch of fabric switch 100 is assigned a switch identifier
(e.g., an RBridge identifier, a Fibre Channel (FC) domain ID
(identifier), or an IP address). This switch identifier identifies
the member switch in fabric switch 100.
Switches in fabric switch 100 use edge ports to communicate with
end devices (e.g., non-member switches) and inter-switch ports to
communicate with other member switches. For example, switch 102 is
coupled to end device 112 via an edge port and to switches 101,
103, 104, and 105 via inter-switch ports and one or more links.
Data communication via an edge port can be based on Ethernet and
via an inter-switch port can be based on the IP and/or TRILL
protocol. It should be noted that control message exchange via
inter-switch ports can be based on a different protocol (e.g., the
IP or FC protocol).
A switch, such as switch 102, stores configuration information
needed to operate switch 102 as an individual switch or as a member
switch of fabric switch 100. Furthermore, switch 102 can
participate in various services and operations, such as network
virtualization (e.g., a virtual local area networks (VLAN)), switch
partitioning, and link aggregations (e.g., a multi-chassis trunk).
Furthermore, switch 102 operates on a plurality of network
protocols of different network layers (e.g., Ethernet, TRILL, FC,
and IP). As a result, switch 102 runs protocol daemons for each of
these protocols. However, to incorporate the services and
operations, the protocol daemons need to be directly modified,
which can lead to conflicts and errors.
Furthermore, each of the operations, services, and the protocols is
associated with one or more attributes. These attribute values
(e.g., parameters) is typically applied to switch 102 when switch
102 powers up. As a result, these attribute values are stored in a
persistent storage so that these values can be retrieved even when
switch 102 is powered off or restarts. With existing technologies,
switch 102 may store such attribute values in a local storage in an
unstructured format (e.g., a string comprising the attribute
values). During the boot up process, switch 102 reads and parses
the attribute values in the unstructured format, and loads the
attribute values into switch memory. Managing persistent storage in
unstructured format is inefficient and requires runtime
structuring.
To solve this problem, switch 102 is equipped with a persistent
storage framework 120 which facilitates structured persistent
storage to the attribute values associated with different
operational units of switch 102 (e.g., modules and services of
switch 102). It should be noted that other switches of network 100
can be equipped with a persistent storage framework and support
persistent storage. In some embodiments, some switch of network 100
may not be equipped with a persistent storage framework. Different
units of switch 102, each of which facilitates an aspect of switch
102's operations, operate on framework 120 in a structured and
modular way. This allows a respective unit to be independently
introduced to framework 120 in such a way that the unit can
interoperate with other units (e.g., modules and services) of
switch 102. Framework 120 supports MDA, OOP, and/or MVC design
patterns to facilitate structured development and operation of the
units in switch 102.
Since the units operate on framework 120 in a structured way, their
associated attribute values can be stored in a persistent storage
in a structured way. In some embodiments, framework 120 uses
Object-Relational Mapping to store the attribute values of the
units in a structured way in an object relational database.
Framework 120 allows different classes to be defined for a unit
during development based on MDA, OOP, and/or MVC design patterns.
Framework 120 supports class models based on UML. In some
embodiments, class models are expressed in YANG, which is a data
modeling language used to model configuration and state data
manipulated by NETCONF. Upon receiving class models (e.g., class
name, attributes, and methods) and their relationships based on
UML, framework 120 automatically generates the corresponding code,
thereby ensuring structure in the operational units of switch
102.
Framework 120 seamlessly maps a respective class to a database
table and vice-versa. Furthermore, framework 120 also seamlessly
represents the relations among the classes (e.g., an association or
a composition) in the database. As a result, when a unit becomes
operational on switch 102 (e.g., when switch 102 powers up),
attribute values associated with a respective class in that unit is
automatically loaded from the database. Moreover, if a class
changes (e.g., a new attribute or a new relationship), framework
120 seamlessly incorporates that change into the database.
Persistent Storage Framework
FIG. 1B illustrates an exemplary persistent storage framework in a
switch, in accordance with an embodiment of the present invention.
In this example, persistent storage framework 120 of switch 102
provides structured persistent storage to the operational units of
switch 102. In some embodiments, switch 102 is coupled to an end
device 114, which can operate as an administrative terminal for
switch 102. Switch 102 runs one or more protocol daemons 140. For
example, switch 102 can run respective protocol daemons for
Ethernet, TRILL, FC, and IP. A protocol daemon facilitates the
services and operations of a corresponding protocol for switch
102.
Switch 102 further includes an input interface 122 to switch 102
(e.g., a graphical user interface (GUI) and/or a command line
interface (CLI). A user can access input interface 122 via end
device 114. The user can obtain information from and provide
instruction to switch 102 via input interface 122. Switch 102 also
includes a configuration daemon 124, which can receive
configuration (e.g., an IP address) for switch 102 from end device
114 (e.g., from a user) via input interface 122. Configuration
daemon 124 provides this configuration information to framework
120. Framework 120 can include a configuration daemon gateway
module 132, which communicates with configuration daemon 124. Upon
receiving the configuration information, framework 120 can identify
different attribute values (e.g., a VLAN identifier) and assigns
those attribute values to the corresponding attribute of an
operational unit of switch 102.
On the other hand, switch 102 can receive an instruction via input
interface 122 to provide its configuration associated with one or
more units. For example, a user can issue a command to show the IP
addresses assigned to switch 102 from end device 114. Input
interface 122 provides this instruction to configuration daemon
124, which in turn, sends an internal command to configuration
daemon gateway module 132 for the requested configuration
information. In response, framework 120 identifies the attributes
(e.g., IP addresses) associated with the requested configuration
information and obtains the corresponding attribute values (e.g.,
assigned IP addresses to switch 120) from a persistent storage.
Configuration daemon gateway module 132 provides the obtained
attribute values to configuration daemon 124. Upon receiving the
attribute values, configuration daemon 124 provides the attribute
values as the requested configuration information to input
interface 122, which in turn, provides the configuration
information to end device 114.
Framework 120 includes a core management module 130, which
facilitates structured persistent storage to the attribute values
associated with different operational units of switch 102 (e.g.,
modules and services of switch 102). Different units of switch 102
operate on core management module 130 in a structured way. This
allows a respective unit to be independently introduced to
framework 120 such a way that the unit can interoperate with other
units (e.g., modules and services) of switch 102. Framework 120
supports MDA, OOP, and/or MVC design pattern to facilitate
structured development and operation of the units in switch
102.
For example, instead of modifying protocol daemons 140, switch 102
can have plug-ins 134 for protocol daemons 140. Core management
module 130 facilitates inter-operations between plug-in 134 and
protocol daemons 140. Suppose that a modification to standard
Ethernet protocol is needed. Instead of modifying the native
protocol daemon of Ethernet, a plug-in for the protocol daemon of
Ethernet can be introduced to core management module 130.
Similarly, to facilitate membership to a fabric switch, fabric
switch module 136 can be introduced to core management module 130.
Fabric switch module 136 allows switch 102 to run a control plane
with automatic configuration capability and join a fabric switch
based on the control plane. Plug-ins 134 and fabric switch module
136 can be developed using MDA, OOP, and/or MVC design patterns,
supported by framework 120.
Since the units of switch 102 operate core management module 130 in
a structured way, their associated attribute values can be stored
in a persistent storage in a structured way. In some embodiments,
core management module 130 uses Object-Relational Mapping to store
the attribute values of the units in a structured way in an object
relational database 150. Core management module 130 allows
different classes to be defined for a unit during development based
on MDA, OOP, and/or MVC design patterns and expressed as a UML
model, and seamlessly maps a respective class to a database table
in database 150 and vice-versa.
Furthermore, core management module 130 also seamlessly represents
the relations among the classes (e.g., an association or a
composition) in database 150. As a result, when a unit becomes
operational on switch 102 (e.g., when switch 102 powers up),
attribute values associated with a respective class in that unit is
automatically loaded from database 150. Moreover, if a class
changes (e.g., a new attribute or a new relationship), core
management module 130 seamlessly incorporates that change into
database 150. It should be noted that a class defined by a user may
not include explicit instructions (e.g., a Structured Query
Language (SQL) query) for inserting and retrieving attribute values
from database 150. The class simply includes an instruction
indicating that persistent storage is required for some operations
and core management module 130 facilitates the object relational
mapping, and the corresponding database operations (e.g., SQL
insert and select).
Attribute Data Types
To facilitate seamless object relational mapping, a persistent
storage framework defines a set of data types for different
categories of attributes. These attributes can be used to define
class attributes of different operational units of a switch. In
some embodiments, the framework can identify these class attributes
expressed in a UML model. It should be noted that such expression
can be represented in various forms, such as graphical, textual,
XML, etc. The framework ensures these attributes are compatible
with an object relational database. As a result, during operation,
the framework can seamlessly map the class attributes to an object
relational database and provide persistent storage to the
attributes.
A data type of an attribute is basic entity provided by the
framework that can be persisted or transported in the object
relational database. A data type is associated with an identifier
(e.g., a name). A data type can be, persisted or ephemeral,
configuration or operational and read-only or read-write. The
framework can serialize or de-serialize a data type to or from:
XML, remote procedure call (RPC), SQL, JavaScript Object Notation
(JSON), and Open vSwitch Database (OVSDB) management protocol.
The framework supports different categories of attributes. Such
categories include, but are not limited to, integers and numbers,
string, date and time, messaging, UML relations, network, and
others. In addition, the framework supports user defined data types
and corresponding attributes. Table 1 includes different categories
of attributes and their corresponding data types supported by the
framework. It should be noted that the categories and data types
listed in Table 1 is not exhaustive. The framework can support more
categories and data types.
TABLE-US-00001 TABLE 1 Data types supported by Persistent Storage
Framework Category Data Types Integers and 8-bit Unsigned Integer
(UI8), 8-bit Signed Integer (SI8), Numbers UI16, SI16, UI32, SI32,
UI64, SI64, 64-bit decimal (Decimal64) Vector variants of all of
the above User-configured variants of all of the above UI32Range
String String, StringVector, StringVectorVector, StringUC Date and
Date, Time, DateTime Time Vector variants of all of the above and
User-configured variants of all of the above Messaging ServiceId,
ResourceId, ResourceEnum MessageType, MessagePriority, LocationId,
SerializableObjectType UML Relations Association, Aggregation,
Composition Network Universally Unique Identifier (UUID), World
Wide Name (WWN), IPv4Address, IPv4AddressNetworkMask, IPv6Address,
IPv6AddressNetworkMask, IPvXAddress, IPvXAddressNetworkMask,
Uniform Resource Identifier (URI) , MACAddress, MACAddress2, Host,
SNMPObjectId (Simple Network Management Protocol (SNMP)) Vector
variants of all of the above and User-configured variants of all of
the above SQL SQLIn, SQLBetween, SQLComparator, SQLExists Other
Union, Bool, BoolUC, BoolVector, SerializableObejct,
SerializableObjectVector ManagedObject, ManagedObjectVector,
Enumeration ObjectId, ObjectIdVector LargeObject, Map, XML
The framework provides extensive list of built-in data types, as
described in conjunction with Table 1. These data types capture the
attribute values (e.g., data fields) of objects. In some
embodiments, the framework includes one or more attributes that
provide run time introspection that allows runtime identification
of classes. Since attributes can be serialized to and de-serialized
from a variety of formats, the framework provides extensive support
for custom behavior overriding in serialization and
de-serialization. Furthermore, the framework supports user defined
data types.
Object Identifier
In the example in FIG. 1B, framework 120 stores attribute values of
different classes in database 150. During operation, a class is
instantiated in switch 102 (e.g., in the memory of switch 102), and
one or more attributes of that instance are assigned corresponding
values. For example, if the class represents a line card switch
102, an attribute can be a MAC address of a port in that line card
(e.g., MACAddress data type). When the line card becomes active, an
instance of the class, which can be referred to as an object, is
created in the memory of switch 102, and framework 120 stores the
attribute values of that object in a table associated with the
class in database 150.
However, a switch can have a plurality of line cards. For another
line card, another object (i.e., another instance) of the class is
created in the memory of switch 102, and framework 120 stores the
attribute values of that other object in the table associated with
the class in database 150. In this way, the same table can store
attribute values of different objects of the same class. To
identify different objects of a class in the table, framework 120
generates and assigns an object identifier (object ID or OID) to a
respective object of a respective class. This object identifier
operates as the primary identifier of that object. In the database
table, this primary identifier is the primary key of that table. It
should be noted that an object identifier is referred to be
associated with a class in a generic sense, which indicates an
object identifier of an object of the class.
FIG. 2 illustrates an exemplary object identifier generated by a
persistent storage framework in a switch, in accordance with an
embodiment of the present invention. During operation, an object
200 of a class is created in the memory of a switch. The persistent
storage framework of the switch creates an object identifier 210
for object 200. This object identifier 210 can be the primary
identifier for object 210 in the persistent storage. If the
persistent storage is an object relational database, the database
can include a table corresponding to the class. The attribute
values of object 200 and object identifier 210 are inserted into
the table. Object identifier 210 can be the primary key for that
table.
In some embodiments, object identifier includes a class identifier
(a class ID or CID) 220 and an instance identifier (an instance ID
or IID) 230. Class identifier 220 represents the class from which
the object is instantiated. In some embodiments, class identifier
220 is generated based on a hash function (e.g., Rabin Polynomial
hash function) applied to the name of the class. Instance
identifier 230 represents that particular instance of the object.
Hence, if two objects of the same class are created, class
identifier 220 of object identifier 210 remains the same for both
the objects. However, the two objects differ in their respective
instance identifier 230. Typically, class identifier 220 and
instance identifier 230 are 32 and 64 bits long, respectively.
However, these lengths can vary.
In some embodiments, instance identifier 230 includes a group
identifier 232, a location identifier 234, a management module
identifier 236, and a serial identifier 238. Group identifier 232
identifies a group in which the switch is a member. For example, if
the switch is a member switch of a fabric switch, group identifier
232 can be a fabric switch identifier, which identifies a fabric
switch. Location identifier 234 identifies the switch in the group.
For example, if the switch is a member switch of a fabric switch,
location identifier 234 can be a switch identifier, which
identifies the switch within that fabric switch. Typically, group
identifier 232 and location identifier 234 are 10 and 20 bits long,
respectively.
Management module identifier 236 identifies the type of management
module is operating the switch. For example, if the switch is
participating in an active-standby high availability protocol
(e.g., Virtual Router Redundancy Protocol (VRRP) and Virtual Switch
Redundancy Protocol (VSRP)), management module identifier 236 can
indicate whether the switch is an active or a standby switch.
Typically, management module identifier 236 is 1 bit long. However,
length of management module identifier 236 can be increased by
incorporating adjacent bits from location identifier 234.
Serial identifier 238 provides identification of a specific
instance of an object and can be a wrapped-around monotonically
increasing number (e.g., an unsigned integer). Typically, serial
identifier 238 is 32 bits long. In this way, object identifier 210
uniquely identifies an object of a class created by a management
module in a switch, which can be in a fabric switch. In other
words, object identifier 210 can be unique among objects, classes,
management modules, fabric switches, and switch locations within a
corresponding fabric switch.
Base Classes
In the example in FIG. 1B, persistent storage framework 120 maps
classes to object relational tables in database 150, and inserts
attribute values of an object of the class into the table.
Framework 120 provides a set of base classes from which a class
created for an operational unit of switch 102 can be inherited
from. These base classes provide a development framework for the
operational units and ensure that the operational units of switch
102 remain structured during operation. In this way, framework 120
can facilitate structured persistent storage to the attribute
values of the operational units.
The framework supports a set of base classes and multiple
inheritance from these base classes. FIG. 3 illustrates exemplary
base classes for supporting a persistent storage framework in a
switch, in accordance with an embodiment of the present invention.
In some embodiments, the most base class 302 is the
PersistableObject class. This class outlines the most fundamental
operations supported by the persistent storage framework of a
switch. Another base class 304, denoted as the ManagedObject class,
is virtually derived from the PersistableObject class. Any object
instantiated from an inheritance chain of the ManagedObject class
can be referred to as a managed object. The framework provides
seamless persistent storage support to these managed objects.
Class 304 outlines the most common attributes and operations of the
objects managed by the framework. In other words, all class
hierarchies derive virtually from the PersistableObject class.
Since a class can inherit from multiple classes and each of these
classes can inherit from the PersistableObject class, there can
potentially be a conflict during execution of a managed object.
This problem is generally referred to as the diamond problem. To
solve this problem, the framework supports virtual derivation from
the PersistableObject class. Another base class 306, denoted as the
LocalManagedObjectBase class, outlines the attributes and
operations locally managed within a switch. For example, a port is
locally managed in a switch.
Base class 308, denoted as the LocalManagedObject class, is
virtually derived from the ManagedObject class and the
ManagedObjectBase class. Hence, the LocalManagedObject class
outlines the attributes and operations of a switch which are
locally and globally managed. For example, a port is locally
managed within a switch and a VLAN configured for the port is
managed globally. In some embodiments, an application (e.g., a
protocol plug-in) running on a switch can specify more base classes
for that application. Typically, base classes are not directly
mapped to the tables of the object relational database. These base
classes provide object relational mapping support. The attributes
(i.e., the data fields) of these classes become part of a
respective managed object derived from these base classes. As a
result, the managed objects can share states and behavior.
In some embodiments, the attributes of a managed object can be any
of the attribute data types supported by the framework, as
described in conjunction with Table 1. The framework also supports
vector variants (e.g., arrays and lists) for a number of the data
types. Furthermore, the framework provides support to check whether
a particular attribute is user configured. As described in
conjunction with FIG. 3, the framework supports hierarchical
managed objects based on inheritance. The framework also supports
weak and strong references to objects. A weak reference does not
protect the referenced object from being destroyed (e.g., by a
garbage collector), unlike a strong reference, which protects the
object from being destroyed.
Object Relational Mapping
In some embodiments, a persistent storage framework of a switch
supports, both one-to-one and one-to-many, association,
aggregation, and composition UML relationships. Association and
aggregation are supported via ObjectID and ObjectIDVector data
types, and ObjectIDAssociation and ObjectIDAssociationVector
attributes, respectively. On the other hand, composition is
supported via ManagedObectPointer and ManagedObectPointerVector
data types and corresponding attributes. In some embodiments, the
framework supports smart pointers and vector to facilitate seamless
development.
FIG. 4A illustrates an exemplary UML model of classes of a switch
with a persistent storage framework, in accordance with an
embodiment of the present invention. In this example, a class 404,
denoted as the Node class, represents network nodes, such as a
switch or a router. Attributes for the Node class includes a
NodeID, which represents an identifier for a node. Since a switch
can be a member of a switch group (e.g., a fabric switch), the Node
class has a relationship with class 402, denoted as the SwitchGroup
class, which represents a group of switches. A switch can be in one
such switch group and a switch group aggregates a plurality of
switches. Hence, the relationship between the Node class and the
SwitchGroup class is a one-to-many aggregation, which is denoted as
"isMemberOf." In this relationship, the SwitchGroup class can be
referred to as the container class since a switch group "contains"
a switch. On the other hand, the Node class can be referred to as a
related class.
Similarly, a switch can include one or more line cards. Hence, the
Node class has a relationship with class 406, denoted as the
LineCard class, which represents a line card. A line card can be in
one switch and a switch includes (i.e., is composed of) a plurality
of line cards. Hence, the relationship between the Node class and
the LineCard class is a one-to-many composition, which is denoted
as "includes." On the other hand, a switch typically has a power
source, which may not be inside of the switch. So, the Node class
has a relationship with class 408, denoted as the PowerSource
class, which represents a power source of a node. Suppose that, at
a time, a power source can power one switch and a switch can
receive power from one source. Hence, the relationship between the
Node class and the PowerSource class is a one-to-one association,
which is denoted as "getsPower."
A power source can be based on alternating current (AC) or direct
current (DC). So, class 408-A, denoted as the ACPowerSource class,
and class 408-B, denoted as the DCPowerSource class, are derived
from the PowerSource class. The ACPowerSource class and the
DCPowerSource class represent AC and DC power sources,
respectively. Hence, based on the getsPower association, a Node can
get power from a generic power source, an AC power source, or a DC
power source. In this UML diagram, since the relationship between
the Node class and class 408 is one-to-one, an object of the Node
class can have only one of the power sources. In this example, the
PowerSource class, the ACPowerSource class, and the DCPowerSource
class can be referred to as the inheritance chain of the
PowerSource class (class 408).
The framework can receive the UML diagram of FIG. 4A and generate
the corresponding classes in a supported programming language
(e.g., C++, Java, C#, etc). Furthermore, the framework generates an
object relational table for the classes in the model. Furthermore,
the framework can generate corresponding auxiliary tables to
represent one-to-many relationships, as well as tables for classes
in an inheritance chain (e.g., class derivations) and for their
corresponding instances (i.e., objects), as described in
conjunction with FIGS. 4C and 4D. In some embodiments, the
framework receives XML representation of classes and their
relationship (e.g., from a user), and generates the corresponding
classes and tables. FIG. 4B illustrates an exemplary XML
representation of a class corresponding to a switch with a
persistent storage framework, in accordance with an embodiment of
the present invention. In this example, XML definition 400
represents the Node class (class 404 of the UML model in FIG. 4A).
XML definition 400 represents class Node as a ManagedObject with
name "Node."
XML definition 400 includes a respective attribute, such as NodeID,
and its type (i.e., data type, as described in conjunction with
Table 1). XML definition 400 also includes one-to-one and
one-to-many relationships for which the Node class is a container
class. For example, a node contains line cards. Hence, XML
definition 400 specifies aggregation "includes" as an attribute,
its type, and the class to which Node is related. It should be
noted that the isMemberOf relationship is not represented in XML
definition 400 even though the isMemberOf relationship to the Node
class. This is because the container class for the isMemberOf
relationship is the SwitchGroup class. Hence, the isMemberOf
relationship is represented in an XML definition corresponding to
the SwitchGroup class (not shown in FIG. 4B).
Persistent Storage in a Switch
Upon receiving XML definitions associated with the classes of a UML
model, the framework creates a respective table for a respective
class, their derivations, their instances (i.e., objects), and
their one-to-many relationships in an object relational database.
FIG. 4C illustrates exemplary tables generated by a persistent
storage framework in a switch, in accordance with an embodiment of
the present invention. During operation, the persistent storage
framework of the switch generates a table 420 for the Node class in
an object relational database. Table 420 includes a column 421 for
an object identifier associated with the Node class. Column 421
includes two columns 422 and 423 for class identifier and instance
identifier, respectively, of the object identifier associated with
the Node class.
Table 420 also includes a column for a respective attribute of the
Node class. For example, table 420 includes a column 424 for a
NodeID of the Node class. Furthermore, since the Node class has a
one-to-one association with the PowerSource class, for which the
Node class is the container class, the framework includes a column
425 for an object identifier of an object of the PowerSource class
(i.e., an object associated with the PowerSource class). Column 425
includes two columns 426 and 427 for the class identifier and
instance identifier, respectively, of the object identifier
associated with the PowerSource class. The framework also creates a
table 410 for the PowerSource class, comprising column 411 for the
object identifier associated with the PowerSource class. Column 411
includes two columns 412 and 413 for the class identifier and
instance identifier, respectively, of the object identifier of the
PowerSource class.
Similarly, the framework also creates a table 440 for the
ACPowerSource class, comprising column 441 for an object identifier
of an object of the ACPowerSource class (i.e., an object associated
with the ACPowerSource class). Column 441 includes two columns 442
and 443 for the class identifier and instance identifier,
respectively, of the object identifier associated with the
ACPowerSource class. In the same way, the framework also creates a
table 450 for the DCPowerSource class, comprising column 451 for an
object identifier of an object of the PowerSource class. Column 451
includes two columns 452 and 453 for the class identifier and
instance identifier, respectively, of the object identifier
associated with the DCPowerSource class.
In some embodiments, the framework creates auxiliary tables to
enforce consistency on columns 426 and 427. For example, the
framework creates an auxiliary table 430 for the derivations of the
PowerSource class (e.g., based on the UML model in FIG. 4A). In
this example, table 430 corresponds to the PowerSource,
ACPowerSource, and DCPowerSource classes. Table 430 includes a
column 431 for the class identifier associated with the derivations
of the PowerSource class. Similarly, the framework creates an
auxiliary table 460 for the objects instantiated from the
derivations of the PowerSource class. In this example, table 460
corresponds to the PowerSource, ACPowerSource, and DCPowerSource
classes. Table 460 includes a column 461 for the instance
identifiers of the objects instantiated from the derivations of the
PowerSource class.
When a class identifier is generated for any class of the
inheritance chain of the PowerSource class, that class identifier
is inserted into table 430. The framework identifies the
PowerSource, the ACPowerSource, and the DCPowerSource classes of
the inheritance chain of the PowerSource class from the UML model
in FIG. 4A and generates class identifiers 432, 433, and 434,
respectively. The framework then inserts class identifiers 432,
433, and 434 into table 430. In this example, an entry in a table
is denoted with dotted lines. Column 431 of table 430 provides
consistency enforcement to column 426 of table 420 (denoted with a
dashed arrow). In some embodiments, consistency enforcement of
column 426 is based on a foreign key constraint on column 431 of
table 430. On the other hand, when the framework identifies an
object of the PowerSource, ACPowerSource, or the DCPowerSource
class, the framework generates a corresponding object identifier
and inserts the object identifier into table 410, 440, or 450,
respectively.
When an object identifier is inserted into table 410, 440, or 450,
the instance identifier of the object identifier is concurrently
inserted into table 460 (denoted with dotted arrow). Suppose that,
upon detecting an object in the memory of the switch, the framework
inserts an object identifier comprising a class identifier 432 and
instance identifier 435 into table 410. Similarly, an object
identifier comprising a class identifier 433 and instance
identifier 444, and an object identifier comprising a class
identifier 433 and instance identifier 445 are inserted into table
440. An object identifier comprising a class identifier 434 and
instance identifier 454 is inserted into table 450. The framework
ensures that instance identifiers 435, 444, 445, and 454 are also
inserted into table 460. Column 461 of table 460 provides
consistency enforcement to column 426 of table 420 (denoted with a
dashed arrow). In some embodiments, consistency enforcement to
column 427 is based on a foreign key constraint on column 461 of
table 460.
During operation, an object of the Node class is instantiated in
the memory of the switch. The framework identifies the object in
the memory and generates an object identifier for the object
comprising a class identifier 464 and an instance identifier 465.
The framework identifies the attribute values of the object, which
includes NodeID 466 and an object identifier of a power source
object. Suppose that the power source for the switch is an AC power
source, and the object identifier comprises a class identifier 433
and an instance identifier 444, as stored in table 440
corresponding to the ACPowerSource class. The framework creates an
entry in table 420 by inserting class identifier 464, instance
identifier 465, NodeID 466, class identifier 433, and instance
identifier 444 into table 420. Since consistency is enforced on
columns 426 and 427, the relational database ensures that class
identifier 433 and instance identifier 444 appear in columns 431
and 461, respectively.
However, even though the Node class is related to the LineCard
class, since it is a one-to-many relationship, table 420 does not
include an object identifier associated with the LineCard class.
The framework creates an auxiliary table to represent the
relationship the Node class and the LineCard class. FIG. 4D
illustrates an exemplary table representing a one-to-many
association, which is generated by a persistent storage framework
in a switch, in accordance with an embodiment of the present
invention. Upon detecting the LineCard class in the UML model in
FIG. 4A, the persistent storage framework of the switch generates a
table 470 for the LineCard class in an object relational database.
Table 470 includes a column 471 for an object identifier associated
with the LineCard class. Column 471 includes two columns 472 and
473 for corresponding class identifier and instance identifier,
respectively, of the object identifier associated with the LineCard
class.
During operation, an object of the LineCard class is instantiated
in the memory of the switch. The framework identifies the object in
memory and generates an object identifier comprising a class
identifier 474 and an instance identifier 475 for the object. The
framework then creates an entry in table 470 by inserting the
object identifier into table 470. Similarly, the framework
generates an object identifier comprising a class identifier 474
and an instance identifier 476 for another object of the LineCard
class, and a third object identifier comprising a class identifier
474 and an instance identifier 477 for an object of the LineCard
class. The framework creates respective entries in table 470 by
inserting these object identifiers into table 470.
In some embodiments, the framework creates an auxiliary table 480
to represent the one-to-many "includes" relationship between the
Node class and the LineCard class. In the relationship, the Node
class is the container class and the LineCard class is the related
class. Table 480 includes a column 481 for an object identifier
associated with the Node class, and a column 484 for an object
identifier associated with the LineCard class. Column 481 includes
two columns 482 and 483 for the class identifier and instance
identifier, respectively, of the object identifier associated with
the Node class. Similarly, column 484 includes two columns 485 and
486 for the class identifier and instance identifier, respectively,
of the object identifier associated with the LineCard class.
Suppose that the object of the Node class, which is associated with
class identifier 464 and instance identifier 465, includes two line
cards. Hence, the object of the Node class include two objects
(e.g., an ManagedObjectVector) of the LineCard class. Suppose that
instance identifiers 475 and 476 belong to these two objects. As a
result, the framework inserts class identifier 464, instance
identifier 465, class identifier 474, and instance identifier 475
into table 480. The framework also inserts class identifier 464,
instance identifier 465, class identifier 474, and instance
identifier 476 into table 480. In this way, the relationship
between the object of the Node class (associated with instance
identifier 465) and two objects of the LineCard class (associated
with instance identifier 475 and 476) is stored in table 480.
In some embodiments, similar to tables 430 and 460, the framework
creates auxiliary table 490 for the derivations of the Node class
(e.g., based on the UML model in FIG. 4A). In this example, table
490 corresponds to the Node class (and its derivations, if any).
Table 490 includes a column 491 for the class identifier associated
with the derivations of the Node class. Similarly, the framework
creates an auxiliary table 492 for the objects instantiated from
the derivations of the Node class. In this example, table 492
corresponds to the Node class (and its derivations, if any). Table
492 includes a column 493 for the instance identifiers of the
objects instantiated from the derivations of the Node class.
In the same way, the framework creates auxiliary table 495 for the
derivations of the LineCard class (and its derivations, if any).
Table 495 includes a column 496 for the class identifier associated
with the derivations of the LineCard class. Similarly, the
framework creates an auxiliary table 497 for the objects
instantiated from the derivations of the LineCard class. In this
example, table 497 corresponds to the LineCard class (and its
derivations, if any). Table 497 includes a column 498 for the
instance identifiers of the objects instantiated from the
derivations of the LineCard class.
When a class identifier is generated for the Node class or the
LineCard class, that class identifier is inserted into table 490 or
495, respectively. The framework inserts class identifiers 464 and
474 associated with the Node and the LineCard classes,
respectively, into tables 490 and 495, respectively. In this
example, an entry in a table is denoted with dotted lines. Column
491 of table 490 provides consistency enforcement to column 482 of
table 480 (denoted with a dashed arrow). In some embodiments,
consistency enforcement of column 482 is based on a foreign key
constraint on column 491 of table 490. In the same way, column 496
of table 495 provides consistency enforcement to column 485 of
table 480 (denoted with a dashed arrow). In some embodiments,
consistency enforcement of column 485 is based on a foreign key
constraint on column 496 of table 495.
On the other hand, when the framework identifies objects of the
Node or the LineCard class, the framework generates a corresponding
object identifier and inserts the object identifier, comprising a
class identifier and an instance identifier, into table 420 or 470,
respectively. When an object identifier is inserted into table 420
or 470, the instance identifier of the object identifier is
concurrently inserted into table 492 or 497, respectively (denoted
with dotted arrow). For example, when the framework inserts an
object identifier comprising a class identifier 464 and instance
identifier 465 into table 420, instance identifier 465 is inserted
into table 492. In the same way, when the framework inserts an
object identifier comprising a class identifier 474 and instance
identifier 475 into table 470, instance identifier 475 is inserted
into table 497.
Similar to table 480, the framework also creates an auxiliary table
to represent the one-to-many "isMemberOf" relationship between the
Node class and the SwitchGroup class, as described in conjunction
with FIG. 4A. That table includes a column for an object identifier
associated with the container class, which is the SwitchGroup
class, and a column for an object identifier associated with the
related class, which is the Node class. The column for the object
identifier associated with the SwitchGroup class includes two
columns corresponding to class identifier and instance identifier,
respectively, of the object identifier. Similarly, the column for
the object identifier associated with the Node class includes two
columns corresponding to class identifier and instance identifier,
respectively, of the object identifier.
It should be noted that the framework distinguishes between a
composition relationship (e.g., "includes" in FIG. 4A) and an
aggregation relation (e.g., "isMemberOf" in FIG. 4A). In some
embodiments, for a composition relationship, the class definition
of the container class includes an attribute of data type
ManagedObject (and/or ManagedObjectPointer), as described in
conjunction with Table 1. If the relationship is one-to-many, the
date type can be ManagedObjectVector (and/or
ManagedObjectPointerVector). In this way, when an object of the
container class is instantiated, the related objects are created
and included in that instantiated object of the container class. On
the other hand, for an aggregation relationship, the class
definition of the container class includes an attribute of data
type ObjectId. If the relationship is one-to-many, the date type
can be ObjectIdVector. In this way, the objects are created
separately, and when an object of the container class is
instantiated, only references to those related objects are included
in that instantiated object of the container class.
Operations of a Persistent Storage Framework
FIG. 5A presents a flowchart illustrating the process of a
persistent storage framework of a switch generating auxiliary
tables for an inheritance chain in a structured persistent storage,
in accordance with an embodiment of the present invention. During
operation, the framework identifies a respective class of a
non-base class inheritance chain (operation 502). The framework
generates a respective class identifier for a respective identified
class (operation 504). The framework generates an auxiliary table
for the classes of the inheritance chain comprising a column for
the class identifiers of the inheritance chain (operation 506) and
updates the table for the classes of the inheritance chain by
inserting the generated class identifiers (operation 508). The
framework also generates an auxiliary table for the objects (i.e.,
the instantiated objects) of the classes of the inheritance chain,
each comprising a column corresponding to the instance identifiers
associated with the classes of the inheritance chain (operation
510).
FIG. 5B presents a flowchart illustrating the process of a
persistent storage framework of a switch generating class tables in
a structured persistent storage, in accordance with an embodiment
of the present invention. During operation, the framework
identifies a non-base class and generates a class table for the
identified class (operation 532). In some embodiments, the
framework identifies the class, and the attributes and operations
(e.g., data members and methods) of the class from a class model
(e.g., a UML model). The framework can receive the UML model from a
graphical or textual input (e.g., a GUI, CLI, or XML file). In some
embodiments, the table is named based on a hash function (e.g., a
Rabin Polynomial hash function) calculated on the name of the
class. The table can also have a prefix "T." For example, if the
name of the class is Node and hash("Node")=xxx, the table name can
be Txxx. The framework adds a column comprising columns for a class
identifier and an instance identifier to the class table for an
object identifier (operation 534), as described in conjunction with
FIG. 4C.
The framework identifies an attribute of the identified class
(operation 536). It should be noted that the relationships for
which the class is a container class are can also be attributes, as
described in conjunction with FIG. 4A. The framework then checks
whether the attribute is a simple attribute (e.g., not a
relationship) (operation 538). If the attribute is a simple
attribute, the framework adds a column for the identified attribute
to the class table (operation 540). If the attribute is not a
simple attribute (e.g., an attribute representing a relationship),
the framework checks whether the attribute corresponds to a
one-to-one relationship (operation 544). If the attribute
corresponds to a one-to-one relationship, the framework adds a
column, which is for an object identifier, comprising columns for
class identifier and instance identifier of the object identifier
(operation 546), as described in conjunction with FIG. 4C.
The framework enforces consistency on the class identifier and the
instance identifier based on the corresponding auxiliary tables of
the related classes (operation 548), as described in conjunction
with FIG. 4C. In some embodiments, the consistency is enforced
based on a foreign key constraint. If the attribute does not
correspond to a one-to-one relationship (i.e., corresponds to a
one-to-many relationship), the framework generates an auxiliary
table for the one-to-many relationship (operation 550) and enforce
consistency on object identifiers in the auxiliary table for the
one-to-many relationship (operation 552). Upon adding a column for
the identified attribute (operation 540), enforcing consistency on
the class identifier and the instance identifier (operation 548),
or enforcing consistency on the object identifier (operation 552),
the framework checks whether all attributes have been checked
(operation 542). If not, the framework continues to identify an
attribute of the identified class (operation 536).
FIG. 5C presents a flowchart illustrating the process of a
persistent storage framework of a switch generating an auxiliary
table representing an one-to-many relationship in a structured
persistent storage, in accordance with an embodiment of the present
invention. Operations described in FIG. 5C elaborates operation 550
of FIG. 5B. During operation, the framework generates an auxiliary
table for the one-to-many relationship (operation 562). In some
embodiments, the name of the auxiliary table is based on the
container table name, related table name, and the relationship
name. For example, if the container table name is Txxx, related
table name is Tyyy, and the relationship name is ABC, the name of
the auxiliary table can be TxxxABCTyyy.
The framework adds a column for an object identifier comprising
columns for class identifier and instance identifier of the
container class (operation 564), as described in conjunction with
FIG. 4D. The framework enforces consistency on the object
identifier (i.e., both the class identifier and the instance
identifier) of the container class based on the corresponding
columns of the container class table (operation 566). Similarly,
the framework adds a column for an object identifier comprising
columns for class identifier and instance identifier of the related
class (operation 568), as described in conjunction with FIG. 4D.
The framework enforces consistency on the object identifier (i.e.,
both the class identifier and the instance identifier) of the
related class based on the corresponding columns of the related
class table (operation 570).
FIG. 5D presents a flowchart illustrating the process of a
persistent storage framework of a switch updating tables in a
persistent storage, in accordance with an embodiment of the present
invention. During operation, the framework monitors the memory of
the switch for object generation of the inheritance chain
(operation 582) and checks whether a new object has been detected
(operation 584). If a new object has not been detected, the
framework continues to monitor the memory of the switch (operation
582). If a new object has been detected, the framework generates an
object identifier comprising a class identifier and an instance
identifier for the new object (operation 516). The frame creates an
entry comprising the object identifier in the table of a class
associated with the object (i.e., the class from which the object
has been instantiated) (operation 588). The framework creates an
entry comprising the class identifier, instance identifier, or both
in corresponding auxiliary tables associated with the object
(operation 590) and continues to monitor the memory of the switch
(operation 582).
Fast Reboot
In the example in FIG. 1B, switch 102 can store configuration
information in a configuration file. Examples of configuration
information include, but are not limited to, network
virtualizations, switch partitions, switch groups, and network
protocols of different network layers. When switch 102 boots up,
the attribute values of the configuration information are applied
to switch 102 by loading the attribute values to the switch modules
(i.e., ASIC chips of switch 102).
With existing technologies, before applying the configuration,
switch 102 validates whether the configuration is correct and
cross-checks whether the configuration includes any conflict.
Moreover, during the boot up process, switch 102 reads and parses
the attribute values stored in an unstructured format (e.g., a
string comprising the configuration information). Switch 102
structures the attribute values during runtime, which is
inefficient. As a result, each time switch 102 reboots, even when
switch 102's configuration information is not changed, switch 102
goes through this extensive configuration process, which can be
inefficient and cause delay to network convergence.
To solve this problem, persistent storage framework 120 loads the
configuration information from database 120 to the switch modules
in switch 102. FIG. 6 illustrates an exemplary fast reboot of a
switch with persistent storage framework, in accordance with an
embodiment of the present invention. During the initial boot up
process of switch 102, switch 102 validates, cross-checks, and
executes the configuration information in configuration file 630.
This configuration file 630 can be a batch file and processed
sequentially (e.g., line by line), in switch 102. In some
embodiments, switch 102 includes a boot-up manager 640, which can
be in framework 120, for managing switch boot up. Boot-up manager
640 loads the corresponding attribute values into switch modules
610 of switch 102. Furthermore, framework 120 stores these
attribute values in database tables 620 in database 150 of switch
102, as described in conjunction with FIGS. 4C-4D.
When switch 102 reboots (e.g., due to a restart), boot-up manager
640 checks whether configuration file 630 has changed (e.g., based
on calculating a file difference and/or hash value). If boot-up
manager 640 detects any change, boot-up manager 640 locates where
the changes are and updates corresponding entries in database 150.
If no change is detected, or the changes have been incorporated,
boot-up manager 640 loads the attribute values from database tables
620 in database 150 to switch modules 610. In this way, boot-up
manager 640 provides a fast reboot by bypassing the processing of
configuration file 630, and its corresponding extensive execution,
cross-checks, and validations of the configuration information. It
should be noted that, in FIG. 6, database tables 620 shows the
class tables since data included in the auxiliary tables are
usually also included in the class tables.
Dependency in Configuration
In the example in FIG. 6, segments of configuration information in
configuration file 630 often depend on each other. Typically,
switch 102 processes the configuration information sequentially
from configuration file 630. A user can enforce dependency in
configuration by including configuration information from
configuration file 630 in a proper order. For example, a port of
switch 102 should be configured before associating the port with a
port channel (e.g., for a trunked link). Hence, the administrator
should include the configuration of the port prior to the
configuration of a port channel in configuration file 630. However,
since boot-up manager 640 of framework 120 bypasses processing of
configuration file 630 during a reboot, when switch 102 reboots,
dependency in the configuration information may not be enforced by
configuration file 630.
To solve this problem, boot-up manager 640 uses dependency maps and
a sequence table determine the order at which attribute values
should be loaded into switch modules 610 from database 150.
Framework 120 generates the dependency maps from the UML models
(e.g., the UML model in FIG. 4A). However, since different
operational units of a switch can be developed separately, a
dependency map may not capture interdependencies among different
UML models. To incorporate such dependency, framework 120 maintains
a sequence table, which includes one or more execution passes
(e.g., steps), and for each pass, one or more features that should
be configured in that pass.
FIG. 7A illustrates an exemplary dependency map generated by a
persistent storage framework in a switch, in accordance with an
embodiment of the present invention. In this example, dependency
map 700 shows inter-dependency among the objects of different
classes. The framework generates dependency map 700 based on the
UML model in FIG. 4A. The LineCard class has a composition
relationship with the Node class, which has an aggregation
relationship with the SwitchGroup class. Furthermore, the Node
class is associated with the inheritance chain of the PowerSource
class. This inheritance chain includes the PowerSource class, the
ACPowerSource class, and the DCPowerSource class.
Accordingly, dependency map 700 shows that the objects of the Node
class depend on the objects of the LineCard class. For example, in
switch 102, boot-up manager 640 should load the configuration
information of the objects of the LineCard class from table 470, as
shown in FIG. 4D, to switch modules 610, as shown in FIG. 6, before
the configuration information of the objects of the Node class.
Similarly, boot-up manager 640 should load the configuration
information of the objects of the Node class from table 420, as
shown in FIG. 4C, to switch modules 610 before the configuration
information of the objects of the SwitchGroup class.
On the other hand, since the objects of the inheritance chain of
the PowerSource class are not dependent on each other, boot-up
manager 640 can load these objects from tables 410, 440, and 450,
as shown in FIG. 4C, to switch modules 610 in parallel. However,
boot-up manager 640 should load the configuration information of
these objects to switch modules 610 before the configuration
information of the objects of the Node class. In this way, during
the fast boot-up process of switch 102, boot-up manager 640 ensures
the configuration information of the objects of the interdependent
classes are loaded to switch modules 610 in a proper order.
However, a dependency map only captures the dependencies expressed
in a UML model. Different operational units of the switch are often
developed separately (e.g., by different development groups). As a
result, a dependency map may not capture interdependencies among
different UML models. Hence, a boot-up manager may not be able to
maintain proper order based only on dependency maps. FIG. 7B
illustrates an exemplary sequence table which provides an order
during a fast reboot of a switch, in accordance with an embodiment
of the present invention. In this example, a sequence table 710
represents the order at which a boot-up manager loads configuration
information to the switch modules. In some embodiments, sequence
table 710 is expressed in XML.
Sequence table 710 includes one or more execution passes (e.g.,
steps), and for each pass, one or more features that should be
configured in that pass. The switch sequentially loads
configuration information of one pass at time, and sequentially
loads attribute values of a respective feature in the order of the
appearance of the feature in the pass to the processing hardware of
the switch. In this way, the switch maintains the proper order
during its fast reboot process.
A collection of attribute values in the configuration information
can be referred to as a feature. Features can vary in the amount of
configuration information (e.g., the number of attribute values)
included in it. For example, one feature can correspond to a column
in a table and another feature can correspond to the entire table
in a persistent storage. The framework can generate the sequence
table by parsing across difference dependency maps and connecting
the common classes. The sequence table can also be generated and
provided to the switch by a user (e.g., a developer).
Sequence table 710 includes rows corresponding to a start execution
pass 720, which indicates it to be the first execution pass, and
subsequent execution passes 722-1, 722-2, . . . , 722-n. Sequence
table 710 also includes columns corresponding to features 730-1,
730-2, 730-3, . . . , 730-m. For a specific pass, one or more
features can be selected (denoted with a check mark). For example,
for start pass 720, features 730-1 and 730-3 are selected. During
the boot-up process, the boot-up manager of the framework first
load features 730-1 and 730-3 of start pass 720 to the switch
modules. The boot-up manager then loads the features of pass 722-1,
then of pass--722-2, and so on. It should be noted that the
features and passes can be represented in a sequence table in rows
and columns, respectively, as well.
In some embodiments, a respective pass is associated with a
corresponding processing indicator (or p. indicator). A processing
indicator indicates whether the features of that pass can be loaded
serially or in parallel. Parallel loading of features can the
reduce boot-up time. In sequence table 710, passes 720, 722-1,
722-2, . . . , 722-n are associated with corresponding processing
indicators 714, 716-1, 716-2, . . . , 716-n, respectively. In some
embodiments, a processing indicator is expressed as a field in an
XML tag.
Processing indicators provide additional flexibility to the boot-up
manager. For example, features 730-1 and 730-3 are selected for
start pass 720 and pass 722-2. In one of the passes, features 730-1
and 730-3 can be loaded serially, and in the other pass, features
730-1 and 730-3 can be loaded in parallel. Furthermore, if some
features in a pass can be loaded in parallel and some others should
be loaded serially, the features that can be loaded in parallel can
be put into a separate pass and the corresponding processing
indicator can be set to parallel.
In some embodiments, sequence table 710 is associated with one or
more scopes 712. A scope defines, for an operational aspect of the
switch, the subset of attribute values of a feature that should be
loaded to the switch modules. Scopes 712 allow sequence table 710
to load different subsets of attribute values of a feature to the
switch modules under different circumstances. Suppose that a
feature indicates VLANs associated with the switch. When the switch
reboots, the corresponding scope in scopes 712 indicates that the
attribute values associated with the entire switch should be loaded
to the switch modules. As a result, the boot-up manager loads all
VLAN configurations. On the other hand, when a single line card
reboots (e.g., taken out and put in), the corresponding scope in
scopes 712 indicates that the attribute values associated with that
line card should be loaded into the switch modules. As a result,
the boot-up manager loads only VLAN configurations associated with
that line card.
Operations of Fast Reboot
FIG. 8A presents a flowchart illustrating the initial boot up
process of a switch with a persistent storage framework, in
accordance with an embodiment of the present invention. In some
embodiments, the boot up process of a switch is managed by a
boot-up manager. During operation, the switch obtains and validates
a configuration file (operation 802). The validation process
includes checking whether the attribute values of the configuration
file correspond to the correct fields. For example, a MAC address
should not be assigned to a VLAN field in the configuration file.
Furthermore, the validation process can include cross-checking
among different fields of the configuration file.
The switch then sequentially reads a line from the configuration
file (operation 804) and identifies the class(es) associated with
the line (operation 804). In some embodiments, the configuration
file is a batch file, which can be processed sequentially. The
switch creates corresponding object(s) and assigns attribute values
to the object(s) based the configuration file (operation 808). The
switch then creates entries comprising corresponding object
identifier and attribute values in corresponding class tables (and
auxiliary tables) in the local persistent storage (operation 810)
and checks whether the configuration file has been processed
(operation 812). If the configuration file has not been processed,
the switch sequentially reads the next line from the configuration
file (operation 804).
FIG. 8B presents a flowchart illustrating the fast reboot process
of a switch with a persistent storage framework, in accordance with
an embodiment of the present invention. In some embodiments, the
fast reboot process is executed by a boot-up manager, which can be
in the persistent storage framework. During operation, the switch
obtains the current and previous configuration files (operation
832) and calculates the difference between the configuration files
(operation 834). The switch checks whether it has detected a
difference (i.e., whether the configuration file has been changed)
(operation 836). In some embodiments, the switch applies a hash
function to the configuration files and compares the corresponding
hash values to determine whether the configuration file has been
changed. It should be noted that the switch can use both file
difference and hash function, or any other technique to determine
the file difference.
If the switch has detected a difference, the user may have changed
the configuration. The switch identifies the line(s) associated
with the difference in the current configuration file (operation
842). The switch then obtains a line (e.g., the first line) from
the identified line (operation 844) and applies the configuration
specified in the line by generating or updating corresponding
objects and associated attribute values (operation 846). The switch
creates or updates entries comprising the corresponding object
identifiers and attribute values in the corresponding class and
auxiliary tables in the local persistent storage (operation 848),
as described in conjunction with FIG. 5D. In this way, the switch
allows partial processing of the configuration file. The switch
checks whether it has applied all identified lines associated with
the difference (operation 850). If the switch has not applied all
the identified lines, the switch continues to identify the next
line from the identified lines (operation 844).
If the switch has not detected a difference (operation 836), the
configuration of the switch is the same as the initial boot-up, as
described in conjunction with FIG. 8A. Since the switch stores the
attribute values in its persistent database, the switch can proceed
with a fast reboot by bypassing the processing of the configuration
file, and its corresponding extensive execution, cross-checks, and
validations of the configuration information. If the switch has not
detected a difference (operation 836) or has applied all the
identified lines (operation 850), the switch obtains its sequence
table (operation 838). The switch then loads the attribute values
of objects to the switch modules from the local persistent storage
in the order specified in the sequence table (operation 840), as
described in conjunction with FIG. 7B. This fast reboot process
allows a fast convergence of the network which includes the
switch.
FIG. 8C presents a flowchart illustrating the process of a switch
with a persistent storage framework using a sequence table for the
fast reboot process, in accordance with an embodiment of the
present invention. Operations described in FIG. 8C elaborates
operation 840 of FIG. 8B. In some embodiments, the fast reboot
process is executed by a boot-up manager, which can be in the
persistent storage framework. During operation, the switch selects
a pass from the sequence table (operation 852) and checks the
processing indicator of the pass (operation 854). If the processing
indicator indicates serial processing, the switch selects a feature
from the selected pass (operation 864) and identifies a respective
table associated with the selected feature from the local
persistent storage (operation 866).
The switch identifies the order of the attributes within the
selected feature based on one or more dependency maps associated
with the feature (operation 868). Here, the sequence table ensures
the proper order among the features of the switch and the
dependency maps associated with the feature ensures the proper
order within that feature. A feature includes the attribute values
whose interdependency is represented in an UML model and its
corresponding dependency map. The switch obtains the attribute
values associated with the selected feature from the identified
tables (operation 870) and loads the attribute values to the switch
modules (operation 872), as described in conjunction with FIG. 7B.
The switch checks whether it has completed the pass (operation
874). If the switch has not completed the pass, the switch
continues to select the next feature from the selected pass
(operation 864).
On the other hand, if the processing indicator indicates parallel
processing, a respective feature of the pass can be processed in
parallel, thereby further speeding up the reboot process (i.e.,
reducing the reboot time). For a respective feature in the selected
pass, the switch identifies associated table(s) from the local
persistent storage (operation 856) and identifies the order of the
attributes within the feature based on one or more dependency maps
associated with that feature (operation 858). For a respective
feature in the selected pass, the switch obtains the attribute
values associated with the feature from the corresponding
identified tables (operation 860) and loads the attribute values to
the switch modules (operation 862), as described in conjunction
with FIG. 7B.
If the processing indicator indicates parallel processing and the
attribute values are loaded into the switch modules (operation
862), or the processing indicator indicates serial processing and
the switch has completed the pass (operation 874), the switch
checks whether the switch has traversed all passes of the sequence
table (operation 876). If the switch has not traversed all passes
of the sequence table, the switch selects the next pass from the
sequence table (operation 852). In this way, using the sequence
table, the switch provides a fast reboot by loading the attribute
values associated with a configuration file of the switch into the
processing hardware of the switch in the proper sequence without
relying on the configuration file.
Exemplary Switch
FIG. 9 illustrates an exemplary switch with a persistent storage
framework and a fast reboot support, in accordance with an
embodiment of the present invention. In this example, a switch 900
includes a number of communication ports 902, a packet processor
910, a persistent storage module 930, a boot-up management module
932, and a storage device 950. Switch 900 can also include switch
modules 960 (e.g., processing hardware of switch 900, such as its
ASIC chips), which includes information based on which switch 900
processes packets (e.g., determines output ports for packets).
Packet processor 910 extracts and processes header information from
the received frames. Packet processor 910 can identify a switch
identifier associated with the switch in header of a packet.
In some embodiments, switch 900 maintains a membership in a fabric
switch, as described in conjunction with FIG. 1, wherein switch 900
also includes a fabric switch module 920. Fabric switch module 920
maintains a configuration database in storage device 950 that
maintains the configuration state of every switch within the fabric
switch. Fabric switch module 920 maintains the state of the fabric
switch, which is used to join other switches. In some embodiments,
switch 900 can be configured to operate in conjunction with a
remote switch as an Ethernet switch.
Communication ports 902 can include inter-switch communication
channels for communication within the fabric switch. This
inter-switch communication channel can be implemented via a regular
communication port and based on any open or proprietary format.
Communication ports 902 can also include one or more extension
communication ports for communication between neighbor fabric
switches. Communication ports 902 can include one or more TRILL
ports capable of receiving frames encapsulated in a TRILL header.
Communication ports 902 can also include one or more IP ports
capable of receiving IP packets. An IP port is capable of receiving
an IP packet and can be configured with an IP address. Packet
processor 910 can process TRILL-encapsulated frames and/or IP
packets.
During operation, persistent storage module 930 stores
configuration information, which can be in a configuration file, of
switch 900 in a table in object relational database 940 in storage
device 950. Boot-up management module 932 loads the attribute
values to switch modules 960 from the table without processing the
configuration file. Boot-up management module 932 also determines
whether the configuration file has been changed during a reboot of
switch 900. In some embodiments, upon determining that the
configuration file has been changed, boot-up management module 932
determines the changed portion of the configuration file and update
the first table in a local persistent storage based on the changed
portion, as described in conjunction with FIG. 8B.
Boot-up management module 932 also maintains the order in which the
attribute values are loaded to switch modules 960. In some
embodiments, boot-up management module 932 maintains the order
based on a sequence table, as described in conjunction with FIG.
8C. This sequence table includes one or more execution passes.
Boot-up management module 932 sequentially loads attribute values
of one pass at time. Boot-up management module 932 also maintains
order of attribute values of a feature based on one or more
dependency maps, which can be based on corresponding UML
models.
Note that the above-mentioned modules can be implemented in
hardware as well as in software. In one embodiment, these modules
can be embodied in computer-executable instructions stored in a
memory which is coupled to one or more processors in switch 900.
When executed, these instructions cause the processor(s) to perform
the aforementioned functions.
In summary, embodiments of the present invention provide a switch
and a method which provide fast reboot for the switch. In one
embodiment, the switch includes a packet processor, a persistent
storage module, and a boot-up management module. The packet
processor identifies a switch identifier associated with the switch
in the header of a packet. The persistent storage module stores
configuration information of the switch in a first table in a local
persistent storage. This configuration information is included in a
configuration file, and the first table includes one or more
columns for the attribute values of the configuration information.
The boot-up management module loads the attribute values to
corresponding switch modules from the first table without
processing the configuration file.
The methods and processes described herein can be embodied as code
and/or data, which can be stored in a computer-readable
non-transitory storage medium. When a computer system reads and
executes the code and/or data stored on the computer-readable
non-transitory storage medium, the computer system performs the
methods and processes embodied as data structures and code and
stored within the medium.
The methods and processes described herein can be executed by
and/or included in hardware modules or apparatus. These modules or
apparatus may include, but are not limited to, an
application-specific integrated circuit (ASIC) chip, a
field-programmable gate array (FPGA), a dedicated or shared
processor that executes a particular software module or a piece of
code at a particular time, and/or other programmable-logic devices
now known or later developed. When the hardware modules or
apparatus are activated, they perform the methods and processes
included within them.
The foregoing descriptions of embodiments of the present invention
have been presented only for purposes of illustration and
description. They are not intended to be exhaustive or to limit
this disclosure. Accordingly, many modifications and variations
will be apparent to practitioners skilled in the art. The scope of
the present invention is defined by the appended claims.
* * * * *
References